1. Field of the Invention
This invention relates to a lighting system which produces either or both a static lighting effect and a chasing light effect. By chasing light effect is meant the optical illusion of moving light in a string or cascade of LED's. This type of lighting display produces a dynamic sensation and is particularly useful as background lighting in casinos, restaurants and other places of entertainment. The invention may also be use in public places to indicate direction of exits or displays. A full on (not chasing) effect may be achieved by running the chase sequence so fast that the human eye cannot perceive any flicker and it appears that the system is static and all on.
2. Description of the Prior Art
In all prior art with LED's, direct electrical current, (DC) is applied in one direction only and therefore a common return conductor is required for the system to operate (i.e. if a four channel system is constructed, five conductors are required; one to each set of LED's and one as a common return conductor).
The return conductor in these systems under full on condition i.e. not chasing, must be capable of handling the sum of the power supplied on the each of the other four conductors. It must therefore be larger or it will limit the practical length that can be run with any one electrical feed.
Systems using LED's have been designed but they all use a common return conductor and individual feed or supply conductors to each set of LED's to produce the chasing effect.
None of the prior art reverses the direction of the current in the electrical conductors to control which of the LED's are illuminated at a particular time. This is the reason that more complicated connectors and a greater number of conductors are required for a chasing effect in other systems.
Manufacturers caution against applying reverse voltage to LED's and some go so far as to recommend using a protective device to ensure that the LED can never experience this condition.
Accordingly, using reverse voltage to the LED's to achieve a four-channel chase with only three conductors represents a new and not obvious use of LED technology.
By using only three conductors and no common return, economical production is possible in continuous lengths exceeding 200 lineal feet.
Installation and replacement of LED's is easy and can be performed with a minimum of equipment. There is also extreme flexibility in the installation of the LED's along the length of the conductors.
This ensures that the product can be competitive with existing tape and tube light systems in the marketplace while offering benefits that no existing system offers.
Incandescent lights may be powered by either alternating current (AC) or direct current (DC) and systems which produce a chasing effect using incandescent lamps are in existence. However, these systems also use a common return conductor. Because a common return conductor is used in these systems, the capacity of the system is inherently limited in terms of the distance the conductors may be run. A five conductor system for four channels is also necessary in these applications.
U.S. Pat. No. 4,164,008 shows LED's in series soldered or welded to etched conductors, a common return conductor is indicated and there are no provisions to reverse the voltage to any of the LED's. This patent is directed towards the clothing market and only intended for use on garments.
U.S. Pat. No. 4,173,035 discloses LED's soldered to a flexible printed circuit board fabricated in layers and of discrete finite lengths. The conductors are etched and require that the LED's be soldered in place, limiting flexibility of lamp spacing and ease of replacement. This system requires five conductors for a four channel chase. At no time is reverse voltage applied to the LED's.
U.S. Pat. No. 4,263,640 shows an incandescent light source light chasing system. It uses a number of incandescent lamps in series attached to discrete wires. The use of four feed wires and a common return is essential to operation.
U.S. Pat. No. 4,908,743 shows a plastic insulator with conductors inserted into continuous slots where the legs of lamps or LED's may also be inserted. However some form of cover is required for any installation and a common return conductor is necessary. There is no mention of using reverse voltage to achieve any special effects.
U.S. Pat. No. 4,997,197 shows LED's mounted to the sides and end of skateboards. Provision is made for chasing/flashing but a common return is again required.
U.S. Pat. No. 4,950,958 shows a round tubular "rope" type incandescent elongate light strip. It is not suited for flat application to surfaces, uses incandescent lamps at fixed intervals, and requires a common return conductor for both static and chasing applications.
U.S. Pat. No. 5,027,037 shows a typical sequencing controller for a chasing light system using pulse width modulation to control dimming. Once again a common return conductor is required and there is no provision for changing the direction of voltage and current to achieve any special effects or control any specific lights.